Re: Buzzin Cams

[QSHIPQ@aol.com]

In a message dated 97-03-10 03:01:06 EST, you write:

<< Bzzzzzzzzzzttttttttttt,  Wrong.
 
 Having raced for too many teams that have turbo cars I know a thing or 
 two about what a turbo engine wants cam wise.
 
 Lift just really does'nt matter, after all your Shoving that charge air 
 into each cyl under pressure.  Duration and lack of overlap are the 
 important things when it comes to turbo cams.   Reasonable lift that's 
 all it takes, which makes for nice ramp profiles abd long duration. If 
 lift was important IMSA tech inspectors would have been able to bust the 
 turbo guys when they had cams that "Bent" the rules.  Audi BTW had a 
 really, really nice one for the firehawk car.....
  >>
Not really...  (the buzzer and Hertz quoted)  Why do most race cars use solid
lifter Cams?  This testimonial, contradicts current and past race history,
audis included.  IMSA cars advantage wasn't really in the cam.  If one was to
take a look in PRINT on the Open Class ProRally Group B cars for instance
(where anything goes, so tuning for power is key), one could find a history
that just totally contradicts the above expertise.  Lift in a turbo car is
THE key factor when building a turbo cam.  We are not talking about massive
gains or losses in HP for a small change in overlap.  Look at a schrick cam
specs vs the cam spec's on the '89.5 turbo car.  What is the difference in
overlap?  What is the difference in lift?  Now if one was to  look
specifically at the "available" valve size increase on the race heads, why
wouldn't one increase the size of the intake vavle?  For the EXACT reason
this S.O.C. argues above, no need to, what you want to do is get the exhaust
gasses OUT and maximize exhaust gas velocity, and turbo efficiency, offseting
the slight overlap necessary to prevent valve float.  The intake air is
pressurized, so given a valve size, one could do two things.  Increase the
size of the valve to increase flow (1), or increase the pressure on the same
diameter valve and increase lift (2).  Every turbo tuner today uses (2)
whenever possible (some restrictions apply based on venue), the exception is
ABT, and they applied N/A theory to a turbo motor thinking it was the same,
now kinda a smile amongst those in the know.  Since most of the turbo folks
here haven't messed with valve size, some thinking on the above argument
deserves consideration.  Give any tuner a call (from Ned to Sport Wheels), I
hardly need to argue the point, I've spent a great deal of time talking to
most of them on this EXACT subject.  

Here's to hoping the buzzer stops, claimed expertise aside.

Scott